Commodities which are sensitive in respect of aroma, particularly ground roasted coffee, are frequently sold to the final consumer in vacuum packs. The vacuum pack usually consists of a multilayer composite sheet including metallized layers and an inner layer of thermoplastic material. The pack is produced from a continuous sheet tube, usually having a tube seam extending in the longitudinal direction, by cutting off portions of the tube. After being filled and evacuated, the tube portion is airtightly closed by transversely directed top and bottom closure seams.
In the case of ground roasted coffee the contents of the evacuated pack are formed into a cuboidal block which is stable in respect of shape. Projecting parts of the sheet tube at the top and bottom are folded flat for the formation of the closure seams. This results in a formation of the top and bottom end regions of the pack which is known as a fin fold. These parts are folded against the top and bottom faces of the coffee block. Roughly triangular flaps projecting at the sides are likewise folded against the top and bottom faces of the block. A shaped product of overall cuboidal shape is thus obtained, which is generally placed in an outer package of cardboard or coated paper.
The invention relates to proposals for enabling composite sheet packs of this kind to be opened without problems.
It is already known to provide a transversely directed tear-open strip under the (top) closure seam of a vacuum pack. At an end of this strip, located at the edge, the welded composite sheet forms a grip tab which can be gripped in order to open the pack with the aid of the tear-open strip. The grip tab is defined by two parallel stamp cuts in the composite sheet, which are made at the side of the end of the tear-open strip (DE-GM No. 75 08 452.5).
This form of opening mechanism for the vacuum pack leads to inadequate airtightness of the pack, so that the vacuum is impaired or destroyed before the pack is used. In addition, this known vacuum packing still does not allow optimum handling of the tear-open strip.
The problem underlying the invention is that of so constructing a pack, particularly a vacuum pack for (ground) roasted coffee or the like, that despite an easily operated tear-open mechanism durable airtightness for the purpose of maintaining the vacuum is ensured.